More CYA Puzzler - Went from 50 to.......50?

[phalcon51]

In my last go-round with CYA I attempted to raise my level from 60 to 70 by adding 2 lbs. of powdered conditioner and a week later it had gone from 60 to 100. So, I drained about 8,000 gal., refilled and adjusted all the other chemicals first. My CYA level read a pretty solid 50. I picked up some liquid conditioner (monosodium cyanurate monohydrate) from Leslie's and added enough yesterday afternoon to go from 50 to 60 according to the Pool Calc (36 oz.). I shook it up well before adding it to 5 gal. of water and then spread it around the pool. I noticed as I poured it in that it's not entirely a liquid like I thought but relatively fine granules mixed in a carrier. Anyhow, I let it mix in for at least 24+ hours and when I tested it today I still got a reading of 50 ppm. It said "Instant Conditioner" on the jug so I assume there's no waiting several days or a week before I can get an accurate reading. So my question is, does the liquid conditioner read the same way in the CYA test as the powdered variety? Any reason I don't see any increase at all in the CYA level?

Here's my current numbers:

FC = 4.5
CC = 0
pH = 7.4
TA = 70
CH = 300
CYA = 50
Salt = 3280 (strips) or 3600 (drops)
Temp = 70
CSI = -0.57 (is this something to be concerned about?)

Thanks,

Gary

 

[257WbyMag]

Are you testing at the same time of day with the same light conditions? It is really easy to go +/- 10 ppm depending on light.

 

[phalcon51]

Yes, I am. Either early morning or late afternoon light, back to the sun just like I always do. I've always been able to get pretty consistent readings.

 

[duraleigh]

The validity of the test is plus or minus 15ppm. That said, I think I can read it better than that but I don't think I would make a 10ppm adjustment.....it's too hard to do and generally not worth it.

 

[phalcon51]

My goal was to get it up to 70 ppm and I didn't want to overshoot it again. I may try to add the same amount for another 10 ppm increase and see what happens.

Gary

 

[HouTex]

I have a similar issue with the liquid conditioner (CYA) from Leslie's. I added a gallon to my pool a couple of weeks ago and it was supposed to be enough to raise my CYA to 80 (for my SWCG) per the pool calculator. I'm consistently getting readings between 60-70, and occasionally I'll get a 50 reading. Could it be something about the Leslie's product, or is it a function of the CYA test being imprecise?

 

[madwil]

the test is + or - 15, I think- so if really 65 could read 50 or could read 80... not a very precise test, unfortunately

 

[phalcon51]

But would it be consistent or would it fluctuate from test to test even if care is taken to duplicate the testing procedure as much as possible?

 

[HouTex]

the test is + or - 15, I think- so if really 65 could read 50 or could read 80... not a very precise test, unfortunately

Sadly, that makes the CYA recommendations in Pool School virtually meaningless. How can I target 80 ppm CYA when I might be there already even though my tests usually read 60-70 with the occasional 50?

 

[duraleigh]

Meaningless????

even though my tests usually read 60-70 with the occasional 50?

I would interpret that to mean your CYA is probably 60-65 but it would be one heck of a stretch for me to interpret your CYA is 80.

I would then CALCULATE the correct dosage to get to 80ppm, put it in the pool, wait a week and retest. My bet is you will get a result that averages 80ppm.

 

[JasonLion]

You do the best you can and use the best reading/guess at the level you have and the corresponding FC levels. The chart was designed with the test precision, or lack there of, taken into account.

 

[dmanb2b]

The test is Plus or Minus 15ppm. If you are consistently at 65 or below, you are not at 80ppm (5+ tests at the same time of day, back to the sun). "Meaningless" is pretty harsh, as we'd have some ugly looking pools and many unstatisfied members if that were the case.

FWIW, I like to poor the mixture out of the tube, back into a container and repour into the tube x3 and take an avg of the 3 readings.

 

[HouTex]

Yes, meaningless was too harsh. But it's still a problem when the test is +/-15. That's a 30 point swing. I'll try adding a little more CYA to try to get consistent readings of 70-80 and hope I'm not at 95.